The present invention relates, in general, to spatial light modulators (SLMs) and, in particular, to methods and apparatus for enhancing the versatility of such SLMs for different modes of operation including printing.
SLMs are well-known devices that are employed for displaying electronically captured images in a variety of applications. One such known SLM is an area LCD of the reflective type, such as commercially available from Colorado Microdisplay, Inc., of Colorado, USA. The SLM is operable for displaying images, for example, in electronic viewfinders. While the captured images that are displayed are suitable for viewing purposes they do not necessarily serve adequately for printing photographic quality prints, especially in a relatively short amount of time. One reason for this is that the light intensity levels associated with the grayscale levels of SLMs of the foregoing type are not usually of the correct levels for producing high quality photographic images. Another reason for this is that SLMs of the foregoing type have a relatively low duty cycle since their red, green and blue images are sequenced fairly rapidly in order to provide dynamic images suitable for viewing, for instance, in a viewfinder mode. Such a relatively low duty cycle, while desirable in terms of viewing, increases the amount of time necessary to print such images and thus is relatively less desirable.
The present invention provides in one aspect, a method of controlling a SLM comprising the following steps: providing a sequential color SLM controller, and a SLM; providing a means whereby said sequential color SLM controller loads optimum values for a single color into control registers of said SLM, during all the field time slots of each video frame; also causing said SLM to modulate light of said single color, during said field time slots of each video frame, whereby the duty cycle for display of said color is increased relative to operation in a normal sequential color mode.
Another aspect of the present invention is an apparatus for controlling a SLM comprising a single color SLM controller, a SLM, and a means for causing said single color SLM controller to load optimum values for a single color into control registers of said SLM during all the field time slots of each video frame; wherein said SLM is caused to modulate light of said single color, during said field time slots of each video frame, whereby the duty cycle for display of said color is increased relative to operation with a sequential color SLM controller in a sequential color mode.
Another aspect of the current invention is a method for controlling a sequential color SLM with programmable grayscale characteristics comprising providing a programmable grayscale SLM; and programming the grayscale characteristic of said SLM to implement a grayscale characteristic that is adapted for printing onto photosensitive medium.